How did Thomas Edison propose to Mina Miller, his second wife?

Mina Miller was born on July 6, 1865, the seventh of eleven children. She met Thomas Edison at the home of a mutual friend of her father and Edison, the inventor Ezra Gilliland. Her future husband claims he taught her Morse code so that they could converse in secret, even while the family watched. This is how Edison claims he proposed marriage and how she responded "yes." The two married on February 24, 1886.

In those prim days they seldom found moments alone. Further, Edison's premature deafness prevented Mina and him from conversing in tones not easily overheard by others around them. The ingenious Edison had a solution: he taught her to send and receive in Morse code, in which he was expert. One night on a chaperoned motor trip to the White Mountains, he tapped out a proposal of marriage on Mina's palm. His training had not been in vain. Mina responded in code with a message that constituted a provisional "Yes" - provisional in that in keeping with the times, September of 1885, her father's approval must first be obtained.